Update table row using modal window

I display list of rows from table on update page, and I want to update each row one by one using Bootstrap modal. I’ve gone through this article but it didn’t work - http://www.yiiframework.com/wiki/806/render-form-in-popup-via-ajax-create-and-update-with-ajax-validation-also-load-any-page-via-ajax-yii-2-0-2-3/

Here is my current code:

Update View Code:

<?php

use yii\helpers\Html;

use yii\helpers\Url;

use yii\widgets\ActiveForm;

use yii\bootstrap\Modal;

?>

<?php $form = ActiveForm::begin(); ?>

    <table class="table">

        <thead>

            <tr>

                <th>Type</th>

                <th>Size</th>

                <th>Action</th>

            </tr>

        </thead>

        <tbody>

        <?php foreach($config as $index=>$value): ?>    

            <tr>

                <td><?= $value->type ?></td>

                <td><?= $value->size ?></td>

                <td>

                    <?= Html::button('Edit', ['value' => Url::to(['site/update', 'id' => $value->id]), 'title' => 'Update Config', 'class' => 'btn btn-default update-btn']); ?>

                </td>

            </tr>

        <?php endforeach; ?>

        </tbody>

    </table>

<?php ActiveForm::end(); ?>

Update Controller:

public function actionUpdate()

    {

        $config = ProjectConfig::find()->where(['project_id' => 19])->all();

        return $this->render('update', [

            'config' => $config

        ]);

    }

And here is modal code:

<?php

yii\bootstrap\Modal::begin([

    'headerOptions' => ['id' => 'modalHeader'],

    'id' => 'myModal',

    'size' => 'modal-lg',

    //keeps from closing modal with esc key or by clicking out of the modal.

    // user must click cancel or X to close

    'clientOptions' => ['backdrop' => 'static', 'keyboard' => FALSE]

]);

echo Yii::$app->controller->renderPartial('_form');

yii\bootstrap\Modal::end();

?>

How can I make the _form dynamic passing the model from controller.